Tuberculosis causes a staggering burden of mortality world-wide, killing 2 million people annually. To cure tuberculosis, prolonged therapy of at least 6 months is required, because antituberculosis drugs do not penetrate well into macrophages, which are a major reservoir of M. tuberculosis. To devise antituberculosis medications that will shorten the duration of therapy, we will use microparticles to target the delivery of enzyme-cleavable lipophilic derivatives of isoniazid and rifampin to infected macrophages. Once inside the macrophage, the microparticles degrade and release the lipophilic drugs, which are then transported across the M. tuberculosis cell envelope. Our specific aims are: 1. To synthesize and characterize palmitic acid derivatives of isoniazid and rifampin. 2. To determine the rates of esterase or amidase hydrolysis of these derivatives. 3. To evaluate the capacity of these derivatives to kill M. tuberculosis. If this proposal is successful, a phase II proposal will be submitted to perform additional studies to evaluate these agents combined with microparticles in cell culture systems in vitro and in animals. This project will explore the feasibility of a strategy that can be applied to the treatment of infection caused by many intracellular organisms, including viruses, fungi and parasites. PROPOSED COMMERCIAL APPLICATIONS: The technology we will develop in this program has the potential to significantly improve the treatment of diseases due to pathogens that reside in macrophages, such as tuberculosis and HIV infection. In the treatment of tuberculosis, targeted-delivery systems of enzyme- cleavable lipophilic drugs are presently not available. This strategy has the potential to increase the efficacy of treatment, reduce the dosage of drugs required, reduce side effects of treatment, improve patient compliance, and minimize development of drug resistance.